1. Technical Field
The present invention relates to the field of tissue removal and tissue grafting. More particularly, the present invention relates to an apparatus and method for the percutaneous cutting and removal of selected portions of tissue from a patient and the possible harvesting and implantation of the tissue portion in the donor.
2. Description of the Prior Art
There are various known methods and apparatus for the cutting and removal of tissue fragments from a human. Each of these, however, suffers from one or more deficiencies.
U.S. Pat. No. 4,832,683 shows an instrument for ultrasonic cutting of bones, with irrigation or suction. However, there is no suction while cutting, no removal of the cut bone or tissue, and no flexibility in the instrument.
U.S. Pat. No. 4,265,231 shows apparatus for drilling a curved hole having a flexible shaft confined in a rigid tubular sheath, but which shows no removal of cut bone or tissue.
U.S. Pat. No. 4,541,423 shows apparatus for drilling a curved hole having a flexible shaft confined in a semi-rigid tubular sheath, but which shows no removal of cut bone or tissue.
U.S. Pat. No. 4,589,414 shows a surgical cutting instrument with a reciprocatory cutting motion, but which has no removal of cut bone or tissue, and no flexibility in the instrument.
U.S. Pat. No. 4,603,694 shows a rotating arthroscopic shaver with suction, but which is not flexible and which has no removal of cut bone or tissue.
U.S. Pat. No. 4,751,922 shows a flexible medullary reamer with a plastic shaft and a guide rod, but which has no suction and no removal of the cut bone or tissue.
U.S. Pat. Nos. 4,798,213, 4,649,918, and 4,142,517 show various apparatus for bone coring.
The present invention is a percutaneous tissue removal apparatus including a flexible drill shaft and means for transmitting motion to the shaft. A cutting tip is mounted on the shaft to cut tissue fragments from the tissue. The tissue fragments are removed by suction along the flexible drill shaft to a location outside the body while cutting. One or more selected components of the removed tissue fragments may be collected for implantation, preferably into the body of the patient from whom they were removed. Because the drill shaft is flexible, the surgeon can guide the cutting tip into various locations within the tissue from a small (percutaneous) incision. The surgeon can cut around arcs or angles, rather than only being able to go in a straight line, to reach any desired location, and to avoid vital tissue which would otherwise be in the cutting path. For example, when removing unwanted tissue inside a knee joint the drill shaft can deform, and is therefore less likely to damage normal tissue or joint surfaces. None of these functions is possible with a straight line system.
The present invention is a percutaneous tissue removal device and method. In the preferred embodiments described below, the apparatus and method are illustrated as used for removal of bone tissue, but such description is for illustrative purposes only. The invention is not limited to the removal of bone tissue and may be used for removal of cartilage, muscle, fetal tissue, etc. It may be used to break up and remove kidney stones, in the gall bladder for a stone or tumor, in the stomach, in the colon to remove a polyp or tumor, etc. It can reach spaces not currently available with the straight line systems currently available.
A percutaneous tissue removal apparatus in accordance with the present invention includes a flexible drill shaft for insertion inside a tissue. A cutting tip is mounted on the drill shaft for cutting the tissue. Either rotating motion or reciprocating motion is transmitted to the drill shaft to move the cutting tip against the tissue to cut tissue fragments from the tissue. While cutting, the tissue fragments are removed by suction to a location outside the body. The drill shaft and cutting tip are small enough to be usable percutaneously. They may also be used for endoscopic, arthroscopic or fiberoptic or open surgery.
Because the drill shaft is flexible, the surgeon can guide the cutting tip into various locations within the tissue from one percutaneous incision. The surgeon can cut around arcs or angles, rather than only being able to go in a straight line, to reach any desired location, and to avoid vital tissue which would otherwise be in the cutting path. The flexible drill shaft also allows the surgeon when working inside a bone, for example, to keep the cutting tip away from the harder outer cortical bone and to remove only the softer inner cancellous bone. None of these features is available with the current straight line cutting devices.
The drill shaft may be made of metal, of polymeric material to reduce friction, or of a composite material. Extensive use of polymers in the drill shaft, its housing if provided, and the cutting tip area reduces friction substantially, thus requiring less energy and generating less heat within the tissue. The drill shaft is drivable by hand (for improved feel) or by motor, at variable speeds based on the need for the tissue removed.
To provide for the collection of the tissue fragments to be harvested, the removal apparatus has an axially extending suction passage along the drill shaft through which the tissue fragments are removed. The suction passage has a smooth lining to keep the tissue fragments or graft material contained and to reduce friction of the harvested tissue fragments. This lining may be the inside diameter of the flexible drill shaft itself, or may be a separate liner sleeve which can be removed and disposed of when it becomes unsanitary or clogged, without having to remove the drill shaft and cutting tip. Alternatively, if a separate guide sleeve or guide rod is used the suction passage may be formed between the drill shaft and the guide sleeve or guide rod. In such a case, the drill shaft may be solid rather than hollow.
The cutting tip is made of a material which is harder than the material to be cut. The cutting tip may be slightly larger in diameter than the drill shaft. The cutting tip may be made of a polymeric material or a composite material. Alternatively, the cutting tip may be made of a ceramic material. The cutting tip is separable from the drill shaft, and several different cutting tips may be provided in varying hardnesses, so that the surgeon can selectively remove various portions of tissue as desired.
By virtue of its flexibility, the flexible drill shaft, when removing bone tissue, may stay within the cortical confines of the bone. Alternatively, it may work with a guide device to control the location of the cutting tip within the bone. The guide means may be a guide rod extending within the flexible drill shaft, or a hollow guide sleeve outside the flexible drill shaft. The guide rod or guide sleeve may be rigid in a particular shape, to fit a particular application; or it may be bendable into a particular shape which it will hold; or it may be selectively rigidifiable into a particular shape in situ. The guide means may include structure for positioning the tip of the flexible drill shaft. The guide means may also be inserted into a separate flexible tube system to guide it to a specific location, then removed, allowing the flexible drill to be inserted.
Fluid may be injected through the flexible drill shaft to a location adjacent the cutting tip to increase the efficiency of the tissue removal and to limit thermal necrosis. Alternatively, a fluid injection passage may extend axially along the flexible drill shaft, the drill shaft. Alternatively, fluid may be injected through the suction passage, alternating with the suction. The fluid injection may be constant or it may be pulsatile in nature. If fluid injection is used, centrifuging of the harvested material may be performed.
Means for collecting one or more selected components of the harvested tissue fragments may include a known trap or filter connected to the outlet of the suction passage. Removed tissue may be centrifuged to separate its components. Thus, the tissue fragments are not merely removed from the body and may be harvested for implantation of the fragments, preferably into the body of the patient from whom they were removed. In order to maintain the sterility of the tissue removed, the entire suction apparatus including the suction passage and the trap or filter is sterilized, and, if necessary, is disposable.
With the present invention all work is done by going percutaneously through the skin to a specific tissue area to minimize the damage to skin, muscle, and bone. For example, when removing bone tissue, trauma is limited to a small opening in the hard outer structural cortical bone, limiting postoperative bleeding from the bone which is difficult to stop, because the small operative hole can easily be plugged after the grafting procedure is completed, preventing postoperative bleeding into soft tissue. There is only intraosseous bleeding, so that fewer complications, and less pain, are likely to arise. The operation does not create stress risers which would weaken the bone. Thus, the present invention provides a safe and efficient way to collect and reuse a patient""s own tissue.
Human tissue grafting works best using the patient""s own tissue as donor material. Therefore, the harvested tissue may be implanted in the donor""s own body for grafting. To implant one or more selected components of harvested bone fragments, for example, a cannula is inserted through the skin and muscle to the area of the bone where the graft is to be placed. A drill or curette is then used to remove a portion of the outer cortical bone. A curette or probe is inserted through the cannula to clear out the area where the graft is to be placed, either in open surgery or through X-ray guidance in percutaneous surgery. The harvested tissue fragments may be packed or compressed into a plug of tissue graft material, of a specific shape, with or without blood or fibrin for adhesion. Or, a retaining material such as a biodegradable mesh may be used to hold the graft material together as a unit. The graft material and its retaining material are then inserted at the graft location in the bone. Alternatively, the graft material is inserted and then sealed in place with a mass of formable polymeric material inserted over the graft material to hold the graft together in position.
A method of percutaneous tissue removal in accordance with the present invention includes the steps of placing within a tissue mass a flexible drill shaft having mounted thereon a cutting tip for cutting the tissue; transmitting motion to the drill shaft to move the cutting tip against the tissue to cut tissue fragments from the tissue; and removing the tissue fragments by suction to a location outside the tissue mass while cutting the tissue. The method may further include the step of controlling the location of the cutting tip within the tissue with a guide rod, the step of collecting one or more selected components of the harvested tissue fragments, and/or the step of implanting the fragments into the body of the patient from whom-they were removed.